JP2013041858A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed wiring board which improves the adhesiveness between a conductor circuit layer and an adhesive layer covering the conductor circuit layer.SOLUTION: A printed wiring board includes: a first insulation layer 11; a first conductor circuit layer 12 formed on the first insulation layer 11; a second conductor circuit layer 13 formed on the first conductor circuit layer 12; an adhesive layer 16 formed on the first insulation layer 11 so as to cover the first conductor circuit layer 12 and the second conductor circuit layer 13; and a second insulation layer 17 formed on the adhesive layer 16. A width of the second conductor circuit layer 13 is wider than a width of the first conductor circuit layer 12 in at least one direction on a plane arranged parallel with the first insulation layer 11. The adhesive layer 16 fills a recessed space 18, which is enclosed by an upper surface 11a of the first insulation layer 11, a side surface 12a of the first conductor circuit layer 12, and a lower surface 13a of the second conductor circuit layer 13, along the side surface 12a of the first conductor circuit layer 12.

Description

  The present invention relates to a printed wiring board.

In recent years, electronic devices have been reduced in size and weight, and accordingly, printed wiring boards mounted on electronic devices are also required to have higher density and multilayers. The circuit is generally formed of a metal (conductor) such as copper, silver, nickel, or chromium, and these metals have weaker adhesive strength with an adhesive than an insulating base material.
Patent Document 1 describes a method of improving the adhesion with a resin insulating layer by performing a roughening process on the surface of a metal conductor layer (plane layer).

JP 2009-76934 A

  When the surface of the conductor circuit layer is subjected to a roughening treatment, the effect of the skin effect occurs when an electric signal flows through the circuit, which may increase the loss. In particular, the higher the frequency of the electrical signal, the greater the influence of the skin effect.

  The present invention has been made in view of the above circumstances, and improves the adhesion between a conductor circuit layer and an adhesive layer covering the conductor circuit layer without subjecting the surface of the conductor circuit layer to a roughening treatment. It is an object of the present invention to provide a printed wiring board that can be used.

In order to solve the above problems, the present invention provides a first insulating layer, a first conductor circuit layer formed on the first insulating layer, and a second conductor circuit layer formed on the first conductor circuit layer. And an adhesive layer formed on the first insulating layer so as to cover the first conductor circuit layer and the second conductor circuit layer, and a second insulating layer formed on the adhesive layer, The width of the second conductor circuit layer is wider than the width of the first conductor circuit layer in at least one direction in a plane parallel to the first insulating layer, and the upper surface of the first insulating layer and the first conductor layer The adhesive layer is filled along a side surface of the first conductor circuit layer in a concave space surrounded by a side surface of the one conductor circuit layer and a lower surface of the second conductor circuit layer. Provide printed wiring board.
The printed wiring board of the present invention includes a plurality of circuit boards each having a conductor circuit layer formed on one side of an insulating base, and each circuit board is laminated by providing an adhesive layer therebetween, and the adhesive layer and the insulation The base material may be a multilayer printed wiring board having an interlayer conductive portion for electrically connecting each circuit board. In this case, the insulating base materials of the two circuit boards laminated via the adhesive layer are the first insulating layer and the second insulating layer, respectively.

  ADVANTAGE OF THE INVENTION According to this invention, even if it does not give a roughening process to the surface of a conductor circuit layer, the adhesiveness of a conductor circuit layer and the contact bonding layer which covers this conductor circuit layer can be improved.

It is explanatory drawing of the printed wiring board of this invention, Comprising: (a) is sectional drawing which shows an example of a circuit board, (b) is sectional drawing which shows an example of a printed wiring board. (A)-(h) is process drawing which shows the 1st form example of the manufacturing method of a circuit board. (A)-(f) is process drawing which shows the 2nd form example of the manufacturing method of a circuit board. It is sectional drawing which shows an example of a multilayer printed wiring board. (A)-(f) is process drawing which shows an example of the manufacturing method of the multilayer printed wiring board shown in FIG. (A)-(c) is a perspective view which shows the example of a conductor circuit layer.

The present invention will be described below based on preferred embodiments with reference to the drawings.
FIG. 1 shows an example of the printed wiring board of the present invention. As shown in FIG. 1A, the printed wiring board 10 includes a first insulating layer (insulating base material) 11, a first conductor circuit layer 12 formed on the first insulating layer 11, and a first conductor. A circuit board 15 having a second conductor circuit layer 13 formed on the circuit layer 12 is provided. In the circuit board 15, the first insulating layer 11 constitutes an insulating base material, and the first conductor circuit layer 12 and the second conductor circuit layer 13 constitute an integrated conductor circuit layer 14. In the illustrated example, the circuit board 15 is a single-sided printed wiring board in which the conductor circuit layer 14 is formed on one surface 11 a of the first insulating layer 11. In the following description, the surface 11a of the first insulating layer 11 on which the conductor circuit layer 14 is formed may be referred to as the upper surface 11a.

As shown in FIG. 1B, the printed wiring board 10 is formed on the first insulating layer 11 (in detail, so as to cover the first conductor circuit layer 12 and the second conductor circuit layer 13 (that is, the conductor circuit layer 14)). An adhesive layer 16 formed on the upper surface 11a) of the first insulating layer 11 and a second insulating layer 17 formed on the adhesive layer 16 are provided.
The adhesive layer 16 and the second insulating layer 17 may be members that cover or protect the conductor circuit layer 14 such as a coverlay. In the case of a multilayer printed wiring board (details will be described later), the second insulating layer 17 is an insulating base material of another circuit board laminated on one circuit board 15, and the adhesive layer 16 connects the circuit boards to each other. It may be an interlayer adhesive to be bonded.
The circuit board 15 in the illustrated example is a single-sided board having the conductor circuit layer 14 on one side of the insulating base material 11, but the present invention is applied to a double-sided board having the conductor circuit layer 14 on both sides of the insulating base material 11. Is also possible.

As shown in FIG. 1, the width W ₂ of the second conductor circuit layer 13 is wider than the width W _{1 of} the first conductor circuit layer 12 in at least one direction in a plane parallel to the first insulating layer 11. Has been. Thus, a concave space surrounded by the upper surface 11 a of the first insulating layer 11, the side surface 12 a of the first conductor circuit layer 12, and the lower surface 13 a of the second conductor circuit layer 13 is formed on the side of the conductor circuit layer 14. 18 is formed. In the printed wiring board 10, the adhesive layer 16 is filled in the concave space 18 along the side surface 12 a of the first conductor circuit layer 12.

An anchor effect is produced between the adhesive layer 16 filled in the concave space 18 and the lower surface 13a of the second conductor circuit layer 13, and the adhesion area of the adhesive layer 16 to the conductor circuit layer 14 is increased. As a result, the adhesive layer 16 is less likely to be peeled off from the conductor circuit layer 14, and the adhesion can be improved.
Thereby, even if it does not perform a roughening process on the surface of the conductor circuit layer 14, the adhesiveness of the conductor circuit layer 14 and the contact bonding layer which covers this conductor circuit layer can be improved. Therefore, the present invention can be suitably used for a circuit for transmitting a high-frequency electric signal, and can be applied to a case where high-speed transmission characteristics are required.
From the viewpoint of the anchor effect, it is desirable that the width W _{2 of} the second conductor circuit layer 13 is sufficiently wider than the width W ₁ of the first conductor circuit layer 12. Furthermore, in view of the ease of circuit formation, dimensional stability, etc., the width W ₂ of the second conductor circuit layer 13 is about 1.2 to 2.0 times wider than the width W ₁ of the first conductor circuit layer 12. Is preferred.

  In the printed wiring board, the second insulating layer 17 is not an essential component, and an insulating coating material such as a coverlay or a resist is used instead of the adhesive layer 16 that bonds the circuit board 15 and the second insulating layer 17 together. The technical idea of the present invention can also be applied when covering the upper surface of the first insulating layer 11 and the surface of the conductor circuit layer 14. In this case, by filling the concave space 18 with the insulating coating material, the adhesion between the conductor circuit layer 14 and the insulating coating material covering the conductor circuit layer can be improved.

  The side surface 12 a of the first conductor circuit layer 12 refers to a portion where the first conductor circuit layer 12 is exposed between the first insulating layer 11 and the second conductor circuit layer 13. In the illustrated example, the side surface 12a of the first conductor circuit layer 12 is substantially perpendicular to the upper surface 11a of the first insulating layer 11, but is tapered such that the width gradually decreases upward, or conversely, the width. It may be an inclined surface with an inverse taper shape in which increases.

  The lower surface 13 a of the second conductor circuit layer 13 refers to a surface on the side where the second conductor circuit layer 13 is laminated on the first conductor circuit layer 12. In the illustrated example, the lower surface 13 a of the second conductor circuit layer 13 and the upper surface 13 c which is the opposite surface are both substantially parallel to the upper surface 11 a of the first insulating layer 11. Further, a side surface 13 b is formed between the lower surface 13 a and the upper surface 13 c of the second conductor circuit layer 13. In the illustrated example, the side surface 13b of the second conductor circuit layer 13 is substantially perpendicular to the upper surface 11a of the first insulating layer 11, but is tapered such that the width gradually decreases upward, or conversely, the width. It may be an inclined surface with an inverse taper shape in which increases.

  The first insulating layer 11 may be a flexible base material such as a flexible resin sheet or a rigid base material such as an impregnated base material as long as it can be used as an insulating base material for a circuit board in a printed wiring board. Examples of the resin used for the flexible substrate include polyimide resin, polyethylene terephthalate (PET), polyester resin, aramid resin, and liquid crystal polymer.

  Examples of the conductor constituting the first conductor circuit layer 12 and the second conductor circuit layer 13 include metals such as copper, silver, nickel, chromium, and aluminum, but are not particularly limited thereto. The first conductor circuit layer 12 may be a laminate of a plurality of conductor layers, and the second conductor circuit layer 13 may be a laminate of a plurality of conductor layers. The conductor constituting the first conductor circuit layer 12 and the conductor constituting the second conductor circuit layer 13 may be made of the same material or different materials.

The shape of the planar pattern (conductor pattern) of the conductor circuit layer 14 on the first insulating layer 11 is not particularly limited. Specific examples include circuit wiring through which signals are transmitted, dummy wiring through which signals are not transmitted, land portions provided at the ends of the wiring, and plane portions spread vertically and horizontally used for ground (grounding). It is done. Although it does not specifically limit as a width | variety of the direction orthogonal to the longitudinal direction of wiring, 10-50 micrometers is mentioned.
FIG. 6A shows a part of a wiring pattern having a longitudinal direction in one direction. FIG. 6B shows an example of a circular land portion. FIG. 6C shows an example of a square land portion.
When the concave space 18 is formed in the wiring pattern, it may be on one side or both sides in the width direction. The concave space 18 may be formed over the entire circumference of the conductor pattern, or may be a part of the circumference, but the concave space 18 may be formed as much as possible to fill the adhesive layer. preferable.

When using a copper clad laminated board (CCL) as a material, the 1st conductor circuit layer 12 can be formed by patterning from the copper foil part of CCL by using the insulating base material of CCL as the 1st insulating layer 11. FIG.
In consideration of miniaturization of the circuit pattern, the thickness of the conductor circuit layer 14 that is the total thickness of the first conductor circuit layer 12 and the second conductor circuit layer 13 is preferably in the range of 3 to 30 μm.

When the second conductor circuit layer 13 is formed by metal plating, the first conductor circuit layer 12 preferably functions as a seed layer when the second conductor circuit layer 13 is metal plated. As the seed layer, nickel (Ni), chromium (Cr), or the like can be appropriately selected and used. Ni is particularly suitable as a seed layer in consideration of the stability of circuit pattern formation, the variety of types of etching solutions, and environmental considerations. In consideration of suppression of film thickness variation and circuit pattern miniaturization, the thickness of the seed layer is preferably in the range of 0.01 to 10 μm.
When using the 1st conductor circuit layer 12 as a seed layer, the thickness of the 2nd conductor circuit layer 13 formed on the seed layer has the preferable range of 3-20 micrometers.

As shown in FIG. 1 (a), the first conductor circuit layer 12 having a width W _1, the method of forming the conductor circuit layer 14 and a second conductive circuit layer 13 having a width W ₂ of interest (where, W Examples of ₁ <W ₂ ) include the following method (1) or (2).

(1) After forming the first conductor circuit layer having the width W ₁ on the insulating base material, a covering layer having the same thickness as the first conductor circuit layer is formed on the insulating base material. method on the first conductor circuit layer to form a second conductive circuit layer having a width W _2, to further remove the covering layer.

The covering layer is formed so as not to cover the upper surface of the first conductor circuit layer. When a part of the covering layer is formed on the upper surface of the first conductor circuit layer, the excess covering layer is removed from above the first conductor circuit layer before the formation of the second conductor circuit layer. The coating layer only needs to be selectively removable as distinguished from the conductor circuit layer, and examples thereof include a detachable resin layer such as a resist.
As a method of forming the first conductor circuit layer and the second conductor circuit layer having the target width W ₁ or W ₂ , respectively, only a range of the target width can be obtained by using a patterned resist or a catalyst. A conductor circuit layer may be formed. Alternatively, after forming the conductor layer with a width larger than the target width (for example, over the entire surface of the insulating substrate), the conductor layer may be patterned by etching or the like to form the conductor circuit layer with the target width.

An example of a method for forming a circuit board according to the above (1) is shown in FIG.
As shown in FIG. 2 (a), starting with on the first insulating layer 11, the first conductive layer 12A which is (entirely over the example first insulating layer 11) formed in a width greater than the width W ₁ of the object Prepare the materials. As this starting material, a single-sided copper-clad laminate (single-sided CCL) having a structure in which a copper foil is bonded to a flexible resin sheet such as a thin polyimide sheet can be used.
Then, as shown in FIG. 2 (b), on the first conductive layer 12A, to form the first resist layer 21 having a width _{W 1.}
Next, as shown in FIG. 2C, the portion of the first conductor layer 12A not covered with the first resist layer 21 is removed by patterning such as etching, and the first conductor circuit layer 12 having the width W ₁ is removed. Get.
Next, as shown in FIG. 2D, the unnecessary first resist layer 21 is removed.
Next, as shown in FIG. 2E, a second resist layer (covering layer) 22 having a thickness equivalent to that of the first conductor circuit layer 12 is formed on the first insulating layer 11.
Next, as shown in FIG. 2 (f), a third resist layer 23 having an opening 23 a having a width W ₂ is formed on the second resist layer 22. The opening 23a is opened such that the upper portion of the first conductor circuit layer 12 is exposed and the second resist layer 22 is exposed on at least one side in the width direction.
Then, as shown in FIG. 2 (g), by filling a conductor into the opening 23a of the third resist layer 23 to form a second conductive circuit layer 13 having a width W _2. Examples of the method for forming the second conductor circuit layer 13 include electrolytic plating, electroless plating, and sputtering. When the conductor constituting the second conductor circuit layer 13 is deposited also above the third resist layer 23, when the third resist layer 23 is removed, excess conductors can be removed together.
Next, as shown in FIG. 2 (h), by removing the second resist layer 22 and the third resist layer 23 that are no longer needed, the circuit board 15 having the target conductor circuit layer 14 can be manufactured. .

A method of forming a first conductive circuit layer having a width W ₁ is not limited to the method shown in FIG. 2 (a) ~ (d) , a resist layer having an opening having a width W _1, the A method of filling the opening with a conductor and then removing the resist layer may be used.
When the thickness of the second resist layer 22 formed in FIG. 2 (e) is smaller than the thickness of the first conductor circuit layer 12, the upper portion of the first conductor circuit layer 12 is buried inside the second conductor circuit layer 13. It becomes the structure. In this case, by ensuring a large thickness of the first conductor circuit layer 12 in advance, a concave space 18 having a required height can be formed along the side surface of the first conductor circuit layer 12.

(2) on the insulating substrate, a first conductive layer serving as a first conductive circuit layer (over the entire surface of for example, an insulating substrate) with a width greater than the width W ₁ of the object formed, the first conductive layer above, after forming the second conductive circuit layer having a width W _2, how the patterning of the first conductive layer, forming a first conductive circuit layer having a width W _1.

As a method of forming a second conductive circuit layer having a width W _2, as the second conductive circuit layer is formed only within the scope of the width W ₂ of the by using such patterned resist and catalyst Also good. Further, after forming a conductor layer with a width larger than the target width W ₂ (for example, over the entire surface of the insulating substrate), the conductor layer is patterned by etching or the like to form a second conductor circuit layer having the target width W ₂ . May be.

An example of a method for forming a circuit board according to the above (2) is shown in FIG.
As shown in FIG. 3 (a), on the first insulating layer 11, with width greater than the width W ₁ of interest (eg, over the entire surface of the first insulating layer 11) to form the first conductive layer 12A. A seed layer made of a thin metal or the like can be used as the first conductor layer 12A.
Then, as shown in FIG. 3 (b), on the first conductive layer 12A, a resist layer 25 having an opening 25a having a width _{W 2.}
Then, as shown in FIG. 3 (c), by filling a conductor into the opening 25a of the resist layer 25 to form a second conductive circuit layer 13 having a width W _2. Examples of the method for forming the second conductor circuit layer 13 include electrolytic plating, electroless plating, and sputtering. By thickening the resist layer 25, the second conductor circuit layer 13 can be formed thick.
Next, as shown in FIG. 3D, the resist layer 25 that is no longer needed is removed. When the conductor constituting the second conductor circuit layer 13 is deposited also above the resist layer 25, when the resist layer 25 is removed, excess conductors can be removed together.
Then, as shown in FIG. 3 (e) and FIG. 3 (f), the first conductive layer 12A which is not covered with the second conductive circuit layer 13 is removed, the first conductive circuit layer having a width W ₁ 12 can be formed. In this step, it is preferable to use a selective etching solution that removes only the first conductor layer 12A and does not remove the other materials, particularly the second conductor circuit layer 13. As the selective etching solution, for example, a nitric acid-based chemical solution can be used for the Ni seed layer.
The first conductor layer 12B in FIG. 3 (e) has the same width as the second conductor circuit layer 13, but the side surface of the first conductor layer 12B is further removed by etching, whereby the first conductor layer 12B in FIG. As shown, the first conductor circuit layer 12 narrower than the second conductor circuit layer 13 is formed.
To the width _{W 2} of the second conductive circuit layer 13 is 1.2 to 2.0 times the width _{W 1} of the first conductive circuit layer 12, the width _{W 1} of the first conductive circuit layer 12, the it may be set to 2 0.5 to 0.8 times the width _{W 2} of the conductive circuit layer 13.
Through the above steps, the circuit board 15 having the target conductor circuit layer 14 can be manufactured.

  FIG. 4 shows an example in which the present invention is applied to a multilayer printed wiring board. The printed wiring board 100 shown in FIG. 4 includes a plurality of circuit boards 15 and 15A in which conductor circuit layers 14 and 14A are formed on one side of an insulating base material 11, and each circuit board 15 and 15A includes an adhesive layer 16 and 16 are laminated, and the adhesive layer 16 and the insulating base material 11 have interlayer conductive portions 32 that electrically connect the circuit boards 15 and 15A.

The circuit board 15 in the printed wiring board 100 has the same structure as the printed wiring board 10 shown in FIG. That is, in at least one circuit board 15, the conductor circuit layer 14 includes a first conductor circuit layer 12 formed on the insulating base material 11 and a second conductor circuit layer 13 formed on the first conductor circuit layer 12. The adhesive layer 16 is provided so as to cover the first conductor circuit layer 12 and the second conductor circuit layer 13. Furthermore, the width of the second conductor circuit layer 13 is wider than the width of the first conductor circuit layer 12 in at least one direction in a plane parallel to the insulating substrate 11, and the upper surface 11a of the insulating substrate 11 and the second An adhesive layer 16 is filled along the side surface 12 a of the first conductor circuit layer 12 in a concave space surrounded by the side surface 12 a of the first conductor circuit layer 12 and the lower surface 13 a of the second conductor circuit layer 13.
Thereby, the adhesiveness of the conductor circuit layer 14 and the contact bonding layer 16 which covers this conductor circuit layer 14 can be improved.
When the insulating base material 11 of the circuit board 15 of the printed wiring board 100 shown in FIG. 4 is made to correspond to the first insulating layer 11 of the printed wiring board 10 shown in FIG. 1, the conductor circuit layer 14 side of the circuit board 15 is used. Further, the insulating base material 11 of the other circuit boards 15 and 15A laminated via the adhesive layer 16 corresponds to the second insulating layer 17 of the printed wiring board 10 shown in FIG.

An example of a method for manufacturing the multilayer printed wiring board shown in FIG. 4 is shown in FIG.
As shown in FIG. 5A, a circuit board 15 having a conductor circuit layer 14 on the upper surface 11a of the insulating base material 11 is prepared. As shown in FIG. 5B, the conductor circuit layer 14 of the insulating base material 11 is prepared. The adhesive layer 16 is formed on the surface 11b on the opposite side. The method for forming the adhesive layer 16 is preferably performed by pasting adhesive sheets formed in a sheet shape in advance, and productivity is improved as compared with the case of applying and drying a liquid adhesive.
Examples of the material for the adhesive layer include polyimide adhesives, epoxy adhesives, and acrylic adhesives. The circuit pattern can be formed after the adhesive layer 16 is formed. However, if the adhesive layer 16 is present during the patterning process of the two conductor circuit layers 12 and 13 having different widths, the patterning may be performed. It is preferable to form a circuit pattern prior to the formation of the adhesive layer 16 because there is a risk that restrictions may be imposed on the method used, the chemicals, and the like.

  As shown in FIG. 5C, a via opening 31 that penetrates the adhesive layer 16 and the insulating base material 11 and exposes the lower surface 12b of the first conductor circuit layer 12 is formed, and then, as shown in FIG. As shown, the via opening 31 is filled with a conductive material such as a conductive paste to form an interlayer conductive portion 32. As the conductive paste, Pb solder, so-called lead-free solder such as Sn-Ag-Cu, anisotropic conductive paste (ACF), a mixture of one or more kinds of silver paste, or a small amount of different metals are mixed. Pasted materials and the like. As a method for filling the conductive paste, a printing method, a spin coating method, a spray coating method, a dispensing method, a laminating method, or a method using a combination thereof can be used.

In the collective laminating step of FIG. 5E, the circuit board 15 which is the lowermost layer may not have the adhesive layer 16 laminated on the back surface 11b. In addition, the circuit board 15 which is the lowermost layer is not limited to a single-sided board having a conductor circuit layer on one side of the insulating base material 11, and a double-sided board having a conductor circuit layer on both sides of the insulating base material 11 can be used. is there. The interlayer conductive portions 32 of the upper circuit board are aligned with the upper surface 13c of the second conductor circuit layer 13 of the lower circuit board, and then stacked on each other.
Further, the circuit board 15A as the uppermost layer may have a single conductor circuit layer 14A.
In the hot pressing process, appropriate temperature and pressure are set so that the adhesive layer 16 sufficiently covers the periphery of the conductor circuit layer 14. The circuit boards 15 and 15A are integrated by the adhesive layer 16 laminated therebetween, whereby a multilayer printed wiring board 100 is obtained as shown in FIG.

  The number of the circuit boards 15 having the interlayer conductive portions 32 serving as an intermediate layer is not particularly limited, and may be one or more. It is also possible to obtain a two-layer printed wiring board by laminating the adhesive layer 16 between the circuit board 15A as the uppermost layer and the circuit board 15 as the lowermost layer.

W ₁ ... width of the first conductor circuit layer, W ₂ ... width of the second conductor circuit layer, 10, 100 ... printed wiring board, 11 ... insulating substrate (first insulating layer), 11a ... upper surface of the first insulating layer , 12: first conductor circuit layer, 12a: side surface of the first conductor circuit layer, 13: second conductor circuit layer, 13a: lower surface of the second conductor circuit layer, 14, 14A ... conductor circuit layer, 15, 15A ... circuit Substrate, 16 ... adhesive layer, 17 ... second insulating layer, 18 ... concave space.

Claims (2)

A first insulating layer; a first conductor circuit layer formed on the first insulating layer; a second conductor circuit layer formed on the first conductor circuit layer; the first conductor circuit layer; An adhesive layer formed on the first insulating layer so as to cover the two-conductor circuit layer, and a second insulating layer formed on the adhesive layer;
The width of the second conductor circuit layer is wider than the width of the first conductor circuit layer in at least one direction in a plane parallel to the first insulating layer,
The adhesive layer extends along the side surface of the first conductor circuit layer in a concave space surrounded by the upper surface of the first insulating layer, the side surface of the first conductor circuit layer, and the lower surface of the second conductor circuit layer. A printed wiring board characterized by being filled.   A plurality of circuit boards having conductor circuit layers formed on one side of an insulating base material are provided, and each circuit board is laminated by providing an adhesive layer therebetween, and each circuit board is provided on the adhesive layer and the insulating base material. The printed wiring board according to claim 1, wherein the printed wiring board is a multilayer printed wiring board having an interlayer conductive portion for electrically connecting the two.

Images